#include <stdio.h>
int main()
{
    int n,i;
    scanf("%d",&n);
    float sum=0.0,t=1.0;    
    for(i=1;i<=n;i++)
	{
        sum+=t/i;
        t*=-1;
    }
    printf("%.2f\n",sum); 
    return 0;
}